When the engineer arrives to service your fire extinguishers, most business owners just let them get in with it and pay little or no attention to what they are doing. This a brief rundown on what a competent engineer should do to each extinguisher.

Firstly, check the service label which carries various information including when the last service was carried out and when the extinguisher is due to be replaced or a discharge-refill test. 

Second, check the body of the extinguisher for damage or rust.

Third. Remove and replace the tamper seal. Ideally this will be a different colour from the previous one which may not be the case if you are using a new company.

Fourth, remove the discharge hose or swivel horn and replace the 'o' ring, this should match the tamper seal and gauge dot in colour.

Five. Remove the gauge dot, carry out a gauge test using an appropriate tool and recover the hole. (CO2 extinguishers do not have a gauge.)

Fifth. weigh it and fill in the service label. 

Finally, give it a dust.

While the above may make it seem simple all engineers are fully qualified and, most importantly, fully insured.